1966-81 Corvette 621 Aluminum BellhousingThis is a brand new exact reproduction 1966-81 Corvette Bellhousing. 168 tooth Aluminum bellhousing. Part # 3899621. Used on vehicles with factory HD 11" Clutch. Has 4 5/8" center hole. It was used on most Chevy Big Blocks, Small Blocks, and 6-cylinder engines. This part was used extensively across the Chevrolet product line.